Some Facebook friends are playing games on Facebook such as Empires & Allies and Hidden Chronicals. I never tried those games or gave them permission to contact me, but I receive annoying daily requests to join.

As I told in my last paragraph, neither Empires & Allies or Hidden Chronicals are on the list, so... how do I block them?
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OsvaldoApr 30 '12 at 15:43

@Osvaldo i have edited my answer to account for that.
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user221287Apr 30 '12 at 15:46

I think I've found it. It's in the "Blocked People and Apps " section, and I was looking in the "Apps games and websites" section. PFF I'll wait to see if it's effective and post the result here.
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OsvaldoApr 30 '12 at 15:47

From the Facebook News Feed click on Apps and Games in the left sidebar, or go to https://www.facebook.com/games. Any requests from friends should appear at the top. Go the upper right corner of the request and click the X that appears. That will hide that request and provide the option of blocking the application, or ignoring all requests from that person.

If you are not receiving requests/invites but it is just appearing your News Feed, and you do not want to see those, you can hide all game stories from particular people, or all stories from a particular game. Just hover over one of those posts in your News Feed, click on the ∨ that appears in the upper right corner of the post, and choose the desired option.